Sorry to hear about your arthritis, but stoked to hear you are still out there snowboarding!
You assessment of getting some Flow bindings is very wise, as they are indeed a lot easier to get into. You do not have to bend down as much as for two-straps, and it's only one pull on the hiback for each binding instead of closing and ratcheting two straps per foot.

The Flow NX2 and Fuse series models all come with Multi-disks, which are designed to be totally compatible with the Burton Channel-system.
For the other Flow models there is a separate Channel-disk available just like UnionInhouse said.

But I would look into the NX2 or Fuse series models; they have the new NASTY Active Strap system, which makes it even easier to get in&out!